The present invention relates to fans, and more particularly to fan blades with structural, mass, and/or flow improvement features.
Fans, such as fans for automotive applications, take a variety of forms. Axial flow fans are the most common type for automotive applications. Historic designs include fans that are manufactured at a given diameter and then blade tips are trimmed to alter a fan diameter, and fans that are manufactured with specific flow optimization at the blade tips and are only offered at a single diameter (e.g., ring fans).
In one aspect of the present invention, it is desired to provide an axial flow fan blade that provides fluid flow improvement, in terms of reduced air recirculation and turbulence that generates acoustic noise, through ribs or other structures located along the pressure and/or suction side of the blade. It is further desired to provide a modular axial flow fan assembly and associated method utilizing fan blades to provide fans at different diameters without destroying or damaging fluid flow modulating structures, such as those at or near blade tips.
Furthermore, cooling systems for automotive applications carry an inherent weight penalty. That is, cooling systems, including fans, must be carried by the automobile and therefore contribute to the mass of the vehicle and the fuel consumption required to move the mass of the vehicle. Moreover, the energy needed to rotate a fan depends in part upon the mass of the fan blades. Fan blades with higher mass require more energy to rotate to perform desired work. Relatively high-mass fan blades also tend accelerate more slowly and may operate at lower speeds for a given energy input, relatively to a hypothetical fan with lower-mass blades. Therefore, fan blades used in automotive applications should be as lightweight as possible. Yet fans must still be structurally sound in order to withstand expected operating conditions over a relatively long lifespan. Historic designs include fans that are manufactured of homogeneous blade material (such as metal or molded polymers), or of a composite material with a “solid” cross-section (i.e., a uniform thickness). Fan blades tend to become less stiff as material is removed, such as by making the fan blades uniformly thinner, which may present challenges in terms of structural integrity and blade lifespan and reliability. It is therefore desired to provide an axial flow fan blade that has a relatively low mass, while maintaining suitable structural integrity, durability and reliability.